For many years it has been an objective of pleasure boat designers to provide a boat design with maximum motion comfort. Another way of expressing such comfort is provision of a smooth ride which avoids the pitching and rolling which occurs as the boat passes over waves. Higher speeds have been the nemesis of the smooth passage of boats through ocean waters particularly when experiencing steep peaks and valleys in waves. Improved hull shapes and configurations have been of primary consideration. Planing hulls, which are subject to slamming and rolling as the vessel passes over waves, are considered poor designs for comfort.
Past efforts to achieve motion comfort for small passenger vessels (up to 120 feet in length) have resulted in multihull boats and ships, such as catamarans, trimarans and proas. Recent configurations in multihull construction have achieved good stability and comfort particularly at lower speeds and not in high seas. Many designs for catamarans use conventional hull shapes. Some use torpedo shaped hulls which create problems related to fluid flow characteristics causing pitching on the surface. Other configurations use multihulls with plural over and under pontoons on each side with at least the lower pontoons being submerged. Boats with such submerged type hulls are termed SWATH type vessels.
The SWATH type vessels have at least two hulls, each with less than 50% buoyancy, which run completely submerged. Because these submerged hulls do not penetrate the surface they have generally been shaped with round cross-section, like torpedoes and nuclear submarines. Although they exhibit the most kindly of motions, they have several major compromises to consider. Swath hulls have greater construction surface area, challenging engine installation, and have greater structural requirements and primarily have limited speeds due to their inability to "read" the average surface level. Speed to length ratios (square root of waterline length in feet divided by speed in knots) much in excess of 3:1 require sophisticated stabilizing fins.
Examples of multihull vessels, boats or ships, with various hull shapes can be found in the following U.S. Pat. Nos.: Des. Pat. No. 274,237 to Stephen A. Edmonds for Catamaran; Des. Pat. No. 289,392 to Harold L. Gary et al for Sailboat; Des. Pat. No. 305,637 to David Emmer for Row Boat Hull; Des. Pat. No. 321,610 to W. R. Price, Jr. for Trimaran Sailboat; U.S. Pat. No. 2,666,406 to V. C. Babcock for Boat Hull; U.S. Pat. No. 3,177,836 to R. Salamin for Boat and Use Thereof; U.S. Pat. No. 3,447,502 to R. Leopold for Marine Vessel; U.S. Pat. No. 3,524,422 to R. B. Fuller for Watercraft; U.S. Pat. No. 3,541,987 to W. Barkley for Water Vehicle with Elevated Deck; U.S. Pat. No. 3,665,885 to A. Javes for Catamaran; U.S. Pat. No. 4,079,688 to G. L. Diry for Displacement Hull; U.S. Pat. No. 4,811,676 to P. Franke for Asymmetric Minimum Resistance Hull; and U.S. Pat. No. 4,870,919 to B. W. Allison for Catamaran Type Boat. None of the above patents teach a hull configuration like that of, nor are they capable of achieving the functional results of the present invention.